Abstract

The Mitidja plain area, located in north Algeria, is one of the main agricultural plains in the Mediterranean basin where water supplies are mainly provided by groundwater resource. Due to the effects of a rapid population increase, followed by an intensification of agricultural activities, a proper groundwater vulnerability assessment became urgent. In this study, the DRASTIC model has been utilized to produce a map of groundwater vulnerability for nitrate pollution. To improve the standard DRASTIC vulnerability map, and to offer an innovative and easy tools for water resource protection and water forensics, the rating classes of the DRASTIC model was modified using the real nitrate concentrations analyzed in 44 groundwater sample while sensitivity analysis was used to change the parameter’s weights. The validation of the standard DRASTIC model shows a coincidence rate of 67% while the validation of the modified DRASTIC model shows a coincidence rate of 82% (improvement of 15%) with nitrates. The results highlighted two main findings: i) the reliability of modified DRASTIC model, and ii) the dependence of nitrate vulnerability on net recharge, aquifer type, soil texture and topography. The proposed approach demonstrated to be more appropriate in assessing the groundwater vulnerability compared to standard DRASTIC proving to be easy applicable and suitable in any arid and semi-arid region around the world.

摘要

Mitidja平原区位于阿尔及利亚北部，是地中海盆地的主要农业平原之一，水源供应主要依靠地下水资源。由于人口快速增长以及随之而来的农业活动加剧的影响，适当的地下水脆弱性评估变得十分紧迫。在这项研究中，DRASTIC 模型已被用于制作地下水易受硝酸盐污染影响的地图。为了改进标准 DRASTIC 脆弱性地图，并为水资源保护和水取证提供一种创新且简单的工具，使用 44 个地下水样本中分析的实际硝酸盐浓度修改了 DRASTIC 模型的评级等级，同时使用敏感性分析来改变参数的权重。标准 DRASTIC 模型的验证显示符合率为 67%，而修改后的 DRASTIC 模型的验证显示与硝酸盐的符合率为 82%（改善 15%）。结果突出了两个主要发现：i) 修改后的 DRASTIC 模型的可靠性，以及 ii) 硝酸盐脆弱性对净补给、含水层类型、土壤质地和地形的依赖性。与标准 DRASTIC 相比，所提出的方法被证明更适合评估地下水脆弱性，事实证明该方法易于适用并适用于世界各地的任何干旱和半干旱地区。ii) 硝酸盐脆弱性对净补给、含水层类型、土壤质地和地形的依赖性。与标准 DRASTIC 相比，所提出的方法被证明更适合评估地下水脆弱性，事实证明该方法易于适用并适用于世界各地的任何干旱和半干旱地区。ii) 硝酸盐脆弱性对净补给、含水层类型、土壤质地和地形的依赖性。与标准 DRASTIC 相比，所提出的方法被证明更适合评估地下水脆弱性，事实证明该方法易于适用并适用于世界各地的任何干旱和半干旱地区。